Influence of the ionic and protein environment on sperm motility activation in the European eel

• Main Author: Vílchez Olivencia, María del Carmen
• Other Authors: Asturiano Nemesio, Juan Francisco, Pérez Igualada, Luz María, Universitat Politècnica de València. Departamento de Ciencia Animal - Departament de Ciència Animal
• Format: Thesis
• Language: English
• Published: Universitat Politècnica de València 2017
• Subjects: envir; geo; European eel
• Online Access: https://doi.org/10.4995/Thesis/10251/90408; http://hdl.handle.net/10251/90408

In general, fish spermatozoa are immotile in the testis. Movement is activated due to the osmotic shock (hypo- or hyperosmotic, depending on fish origin: freshwater or sea water species) experienced when they are released into the external medium. However, there is no consensus regarding the mechanisms that occur after activation. The aim of this project was to study the importance of the environmental ions and proteins on the activation of European eel sperm, and to apply this knowledge to the improvement of sperm quality preservation. Our results demonstrated that there was a notable reduction in sperm motility when either Na+ or K+ was removed from the seminal plasma, but not when they were removed from the activation media. Therefore, our results demonstrated that the presence of Na+ or K+ in the seminal plasma is necessary for the preservationof sperm motility in European eel. However, the presence of Na+ or K+ in the activation media is not essential for the initiation of sperm activation. In contrast, the presence of the ion Ca2+ in the seminal plasma (or the activation media) was not essential for sperm motility activation in this fish species. Moreover, several authors have hypothesised that the hyperosmotic aquatic environment causes an efflux of water through the spermatozoa membrane, and this efflux causes an increase in the intracellular ion concentration (due to the decrease in cellular volume). However, this hypothesis has never been proven. In this study, sperm size (sperm head area) was studied pre- and post-activation in sea water, and in different conditions. For the first time in a marine fish, a significant decrease in sperm head area post activation in sea water was demonstrated. Also the results of this thesis show a notable reduction in sperm head area when either Na+ or K+ was removed from the seminal plasma, as well as a marked reduction in motilityed. Thus, our results demonstrate that the presence of K+ and Na+ in the seminal plasma is important for the preservation of sperm motility ...